1. Field of the Invention
The present invention relates to an exhaust muffler for a vehicle. In particular, the present invention relates to an exhaust muffler for a vehicle formed in a double structure by an outer sleeve and an inner sleeve.
2. Description of the Related Art
Conventionally, what is employed is an exhaust muffler for a vehicle in which the outer circumferential portion of the exhaust muffler is formed in a double structure by an outer sleeve and an inner sleeve, in order to suppress noises or heat emitted from the outer circumferential portion. With such an exhaust muffler, a sound absorbing material such as glass wool is packed between the outer sleeve and the inner sleeve. Since the sound absorbing material also serves as a heat insulating material, the temperature of the outer sleeve becomes lower than that of the inner sleeve. Accordingly, there is a difference between the thermal expansion amount of the outer sleeve and that of the inner sleeve.
In order for the difference of the thermal expansion amount to be tolerated, the inner sleeve has its one end portion supported via a support ring so as to be slidable relative to the outer sleeve. Thus, it is structured to tolerate the elongation of the inner sleeve relative to the outer sleeve. There is Prior Technique Document JP 8-61046 A.
Meanwhile, assembly of the inner sleeve to the outer sleeve in order for the elongation of the inner sleeve relative to the outer sleeve to be tolerated necessitates the support ring. Therefore, an increase in the number of components results. Further, it is troublesome to fix the support ring to the inner sleeve by welding. That is, with the exhaust muffler formed in a double structure by the outer sleeve and the inner sleeve, it is difficult to improve productivity, and an increase in costs results.